Energy efficiency is a key issue for mobile communication networks, since reduced power consumption leads to a prolonged battery lifetime for battery-operated terminals. Today, energy efficiency is considered in terminal design, and power saving schemes such as discontinuous reception (DRX) are utilized in order to reduce power consumption by limiting the time a terminal has to monitor downlink (DL) transmissions. With regard to uplink (UL) transmissions, it has been observed that the power consumption related to UL transmission increases with the number of transmissions. However, so far terminal energy efficiency is not taken into account in UL scheduling.
With evolving fourth-generation (4G) wireless technologies, including for instance complex modulation algorithms and advanced coding schemes, the receivers require computationally complex circuitry that quickly drains the terminal on battery power, thus limiting the use of enriched 4G services. Thus, energy efficiency is also important when designing the air interface and the networks.